Baikal basin
Appearance of rotan in Gusino-Ubukunskiye Lakes is an example of self-invasion in the basin of Lake Baikal. The staff of "Baikalrybvod" (Baikal Fish Inspection) began recording rotan since 1979. In the middle of June 1980 a sample of rotan was caught in a small bay of the eastern part of the lake near Rybpunkt settlement. In 1981 rotan was noted in other lakes of Gusno-Ubukunskaya group. In Lake Gusinoe rotan was evidently unintentionally introduced during the last release of the young of wild carp from Khabarovsk fish farm in 1969. Sorting of the young of wild carp from the young of "weed" fishes in fish farms is laborious and not secure. The insufficient purity of stocking material is the reason of rapid dispersal of rotan in the European part of the USSR as well, where it becomes devastator of pond fishery causing serious harm to commercial fishes of natural water bodies. In 1982 there appeared information of catching rotan from Selenga River in the region of settlements Oshurkovo, Tataurovo and Talovka below Ulan-Ude (Pronin, 1982).
In catches of 1979 rotan in Lake Gusinoye was recorded as a rare species. In 1986-1991 it became a common species (Pronin, Litvinov, 1994). The supposition that it was introduced into the lake during discharge of live fish tank in 1969 with wild carp from ponds of Khabarovsk fish farm was supported by cluster analysis and parasitological analysis. High infection by cestode Nippotaenia mogurndae Yamaguty, a specific parasite of rotan indicates clearly its introduction during introduction (acclimatization) because in aquarium fish breeding helminths with a complex cycle are not retained (Pronin, Litvinov, 1994). Later it became widely spread in delta of Selenga River, Posolsky Sor, Proval Bay. In 1996 rotan inhabited littoral of the southern and middle hollows of Lake Baikal. This was to a large extent favoured by warm summer seasons of 1992-1995 and lack of competition of aboriginal speices in connection with their low abundance. Predatory species (taimen, lenok, pike and others) capable to "control" abundance of rotan are on the verge of extinction. Further increase of abundance of rotan will lead to notable negative consequences, primarily because it major habitation localities are shallow water bays and near delta areas of large rivers, i.e. feeding areas of omul and other commercial fishes in the first year of life. Without decisive measures littoral of the lake will soon be definitively colonized by rotan. In the future growing impact of this predator on endemic fauna of cottoid fishes from Baikal is possible. At present, further extension of its distribution range in Lake Baikal is noted (Matveyev, 1997; 2001; Skryabin, 1988; Litvinov, 1990; Litvinov, O'Gorman, 1996; Sideleva, 2001). Its regular spread out from river mouth to river mouth of middle-sized and small rivers permits predicting its appearance in the littoral of south-eastern coast of Southern Baikal. Probably its penetration and expansion of rotan to bays of Irkutsk water reservoir and Maloye More, where it may find favourable conditions and its abundance may grow rapidly (Bolonev et al., 2002).
According to the results of the expeditions of the past few years (Bolonev et al., 2002), abundance of rotan in water bodies of Baikal Basin declines in the recent years. Regulating factors are predators for which rotan is a major kind of food (pike, perch, gulls) and natural factors among which the major one is the absence of warm water habitats and flow through the water bodies restricting expansion and increase of rotan abundance in south-western direction. It is no mere chance that in the coastal zone of Lake Baikal within Irkutsk Region only single occurrences of this introduced species have been recorded. However its dispersal in river mouths of middle-sized and small rivers of south-eastern coast of Lake Baikal should be expected. As has been noted above, it is not improbable that there may be danger of expansion of rotan in bays of Irkutsk reservoir and Maloye More where it will find favourable conditions and where its numbers will increase rapidly. But how does it happen that rotan relatively rapidly invades nearly every suitable water body situated close to the one already inhabited? Possible factors leading to transfer of rotan from water body to water body is sticking of eggs to the body of water fowl (domesticated and wild), which may be due to sticky filaments characteristic of eggs of rotan and also transfer by sportfishermen as a bait and, moreover, it easily endures transportation at long distances.
It has been established that in those water bodies where predatory fishes (pike, perch) are absent rotan becomes a common species. In such water bodies it usually displaces roach, dace and even crucian carp that before the invasion of rotan was mass species, although both species of Carassius in the majority of water bodies meet competition with rotan.
In the water bodies inhabited by many fish species including also predators, abundance of rotan is low, because there are nearly no free food resources and invader species have small chance to survive and the more so to increase their abundance when invading such water bodies. It inhabits mostly coastal zone, in macrophytes and has no pronounced effect on the composition of ichthyofauna of these water bodies. Nevertheless many authors (Shatunovsky et al., 1988, Alimov et al., 1998; Pronin et al., 1998) suppose that unless urgent measures are undertaken to prevent spreading of rotan, it may soon become the only object of sport fishing in many water bodies. Thus, the necessity to regulate abundance of rotan in water bodies is evident. For that purpose breeding of predators feeding on rotan (where possible) and search for new biological and other methods of rotan reproduction control are necessary.
Local populations of rotan in many lakes have peculiar age structure. Numbers of separate populations (generations) of fishes usually decline with age, i.e. yearlings are most numerous, next in numbers are 1+-2+ classes and then numbers of each subsequent age class declines steadily as a result of natural mortality. In rotan, the whole population in a separate water body may consist of 2-3 age classes, the generation of a single year (reproductively successful) is often predominant.
According to the data of Bolonev et al. (2002) in the basin of Lake Baikal rotan had the highest abundance in those water bodies of the Selenga River delta that had less current. Lakes had relatively complex configuration and are formed in the sites of gravel excavation and are situated 50-70 m from the main river bed of the Selenga River, are well warmed and are rich in vegetation.
However maximum peak of abundance - 6 individuals per a square meter was established by special investigations in 1986 through 1989 in an oxbow lake in the region of Shamanka stream inhabited apart from rotan also by roach and loach. In some lakes, oxbow lakes and streams it constituted 40 to 96 % of the total numbers of fishes (Litvinov, 1993; Pronin, et al., 1998). The same situation was observed in Posolsky Sor and Proval Bay of Lake Baikal where it became common species predominant in a number of coastal lakes of Lake Baikal Region (Lake Baklanye, and others), was noted regularly in gill-net catches in Selenga shallow water to a depth of 30 m. In sport ice-fishing for omul and grayling in Lake Baikal, rotan was caught by fishing rod opposite settlements Turka and Maksimikha. In the middle of September 1997 in the mouth of the Kiki River (near Gremyachinsk) several individuals of rotan 10 to 20 cm in length were caught. In the end of June - beginning of July 2000 one specimen of rotan was found in Dagary Cove (Northern Baikal) at a depth of 8-11 m, the only fish was female weighing 250 g caught by omul net. Rotan occurs at the beginning of August also on the western coast of Lake Baikal off the biological station "Bolshiye Koty" of Irkutsk University. Rotan had probably crossed Lake Baikal during transportation of juvenile fish from Posolsky Sor for experiments at the biological station. Rotan was not recorded south of Posolsky Sor in continental catches in mouths of rivers Mishikha, Kholodnaya and Snezhnaya. It is absent in the Pereyemnaya River (Baikal Reserve) either.
In Lake Gusinoye, where expansion of rotan through water basins of Lake Baikal had actually started, the major mass of rotan is concentrated in the region of Gusinoye Lake (southern part of the water body) with relatively numerous shallow water areas thoroughly warmed and rich in aquatic vegetation. It appeared in the northern extremity of the lake in the region of entry of warm waters from Gusinoye Lake Power Station, where it had not been noted before. However, its total abundance in the recent years declined considerably. It was with an effort that in August 2001 two dozens of specimens 3 to 8 cm in size were caught.
Nearly all water bodies adjoining Ulan-Ude including oxbow lakes on the left coast and down the stream of the Selenga River (Oshurkovo, Tataurovo and Talovka) are inhabited by rotan. Appearance of rotan in the fast-running mountain Turka River was surprising. However it inhabits not the river but numerous shallow water overflows, thoroughly warmed and marshy with a characteristic smell of hydrogen sulphide. Judging by the abundance of juveniles condition for rotan are quite favourable here.
Rotan has successfully adapted to the environmental conditions in the delta of the Selenga River and they are flourishing in the still-water areas. Their success in colonizing the delta suggests that they will be able to establish populations at the mouths of most rivers entering Lake Baikal and in all of the shallow-water bays. Although the cold water and great depths of Lake Baikal were thought to preclude colonization of the main lake basin by rotan, they have reportedly been captured at 35 m in the open lake (pers. comm. from commercial fishermen to A. Litvinov). Highest densities of rotan were found in oxbow lakes where densities sometimes exceeded 4,000 fish per ha (Litvinov, O'Gorman, 1996).
In 1998-1999 single individuals occurred in control catches in Lake Bolshoye Miassovo (closed internal-drainage) in
South Urals (Pereskokov, 2000).
There is evidence that this species became widely spread in south-eastern
Kazakhstan and eastern
Uzbekistan (Borisova, 1972; Vorobyeva, 1974; Seleznev, 1974; Smirnova, 1974; Diarova, 1975). It was noted in the basin of Ili River in shallow places of its plain section with tributaries where it was introduced as a result of acclimatization of white amur (Dubitsky, Rusinov, 1971). However since the first years of filling of Kapchagai Reservoir this species was no longer noted for Ili River basin. It is assumed that P. glenii could have been overlooked because of an abrupt decline in the numbers as a result of changing hydrological regime of the river (Dulravets, Glukhovtsev, 1983).
In water bodies of the European part of Russia rotan has been recorded since the beginning of the
20th century.
Baltic basin.
In 1912 it was brought by naturalist Ippolit Zalivsky from Zeya River to Lisii Nos settlement (St. Petersburg Region) where it was maintained in an aquarium, after which in 1916 it was released in a garden pond where it was breeding (Nabatov, 1914; Dmitriyev, 1971). In the second decade of the 20th century rotan was released by aquarians into small water bodies in the region of Sestroretsk and was spread in the coastal zone close to Petrodvorets and Gorskaya station (Lindberg, 1971; Kudersky, 1982). It inhabits, besides the coastal zone of the Gulf of Finland and water bodies of adjoining territories, also in ponds of parks of St. Petersburg (Kudersky, 1998).
Rotan is noted in the Baltic basin in Kaliningrad Region in the basin of the Pregolya River (Diripasko, 1996, 1997). The first specimen of Amur sleeper was caught by the author on June 11, 1982 in Lake Inzgener (south-eastern part of Kaliningrad). This lake belongs to the Baltic Sea basin and it is connected with the River Pregel falling down to the Vistula Lagoon (Vislinckij zaliv) of the Baltic Sea. It also probably occurs in Daugava River (Kautman, 1999). In the Vistula River basin rotan was discovered for the first time in the Ukraine in the Vishnya River (tributary of San) on 23.06.1988. (Movchan, 1989). In Poland it was registered for the first time in 1993-1994 in water bodies of the old river bed of the Vistula River in Delnim and Kazimierz Dolny (Antychowicz, 1994; Terlecki, 1995). At present six isolated localities of the rotan occurrence in the basin of the Vistula River and Western Bug in Poland (Brylinska, 2000).
Black Sea basin.
In the basin of the
Danube River
rotan was registered in Eastern Slovakia (Kautman, 1999). According to
V. Luskova (pers. comm. 2002), it is numerous in Danube tributaries in Moravia.
In the recent years it began intensively spreading in the
Transcarpathian region (Ukraine) (Korte et al., 1999). It was found in
oxbow lake of the Latoritsa River (caught on 29.08.1999) (Tisza River basin)
and the Chop Lake (caught on 5.06.1999) (note of the editor to the paper by
Moshu & Guzun, 2002). Recorded in Tisza River in Hungary (pers. comm. by Hensel
in Kautman, 1999). Thus, according to the observations of Litvinchuk and
Borkin (2002) it did not occur in water bodies in the vicinity of Chop, Bateva
and Mukachevo in 1996, but was abundant in 2000.
In the basin of the
Dniester River up the stream from the dam of Novodnestrovskaya Power Station up to the very upper reaches it is spread everywhere and quite common (Moshu & Guzun, 2002; authors' data).
In the basin of the
Dnieper River it is known from small rivers and ponds and water reservoirs in the vicinity of Kiev (note of the editor to the paper by Moshu & Guzun, 2002; Sabodash et al., 2002).
In the
Don system, rotan is known from ponds in Lipetzk Province (Kozlov, 1993), from the Voronezh River (Matyrskoje Reservoir) at the town of Gryazi (Mishon, 2000), and in some lakes in Voronezh Province (Gladkikh et al., 2000; Delitsyn, 2001).
Caspian Sea basin
Volga River. In 1948 rotan was brought to Moscow by participants of the Amur expedition. Next year the fish was in aquariums of many Moscow aquarians. Quite probable are other cases of introduction of rotan from aquariums into water bodies of Moscow and its suburbs (Golubtsov, 1990), the more so because rotan at that time was sold at Moscow bird market, where it was passed off as "Amur goby" (Tsepkin, 1999). It is very hardy and spread widely in Moscow ponds, sandpits, small lakes and other small closed water bodies with abundant vegetation. Its numbers are high everywhere. In the periods of high spring floods it spreads from these water bodies into rivers (Sokolov, Tsepkin, 1992).
In "Ozero Glubokoye" reserve, Moscow Region, rotan appeared in 1950. It is assumed that 4-6 specimens were released in a pond of Tarakanovo estate in the vicinity of Zvenigorod, Moscow Region where by 1961 it bacame abundant (Spanovskaya et al., 1964). Later rotan invaded also many other ponds situated close to Lake Glubokoye. In the lake the fish was noted for the first time in 1976. In 1981 in was common (Manteifel, Bastakov, 1986). In the spring-summer period rotan actively consumed larval and even some adult amphibians, which may be the reason of suppression of separate species in Lake Glubokoye. At present rotan occupies nearly all stable ponds (apart from three) and shallow area of Lake Glubokoye. Colonization of water bodies by rotan in this region continues. Thus among 26 permanently observed water bodies 6 water bodies inhabited by rotan were recorded in 1996, 7 in water bodies in 1997, and 8 such water bodies in 1998 (Reshetnikov, 2001).
Interest of aquarians in this fish is quite understandable. It survives well in cold water aquariums, in small ones (5 liters for a couple of fishes) and breeds there.
At present, as a result of uncontrolled spread out, rotan invaded many water bodies of the basin of the middle Volga River, Oka and Kama. Temperate climate, the regions of our country rich in reservoirs and lakes, man-made ponds and sandpits where sand and gravel were procured for building and road construction, abundant food, all these factors wide distribution of this fish in the Moscow Region (Korobeinik, 2001).
Rotan penetrated Gorky Region as a result of dispersal of the "Moscow population" and accidental introduction in 1970 in Ilevsky fish farm with the Amur carp. From growth ponds it penetrated flood plain of the Sarma River (Zaloznykh, 1984).
It inhabits shallow water regions of Saratovskoye and Kuibyshevskoye reservoirs. In 1981 rotan was discovered in Sviyazhsky Bay of Kuibyshev reservoir. In Saratovskoye reservoir it was noted for the first time in 1983. At present a large number of this fish is observed in some flood plain lakes of Saratov reservoir. Abundance apparently increases (Kozlovsky, 2001).
In the Volgograd Reservoir, it appears for the first time in spring 1996 at Vol'sk. According to the data of Naumenko (2002), rotan is mostly abundant in the shallow left-bank part of the reservoir from the town of Volsk to the village of Kvasnikovka, as well as in left-bank tributaries of the Volgograd Reservoir and in shallow lakes connected to the reservoir.
In Mordovia (Oka River) it is spread everywhere in stagnant waters. In 1979 this fish was reported for the first time from Temnikovsky Region, in 1981 this species was recorded in the basin of Sura River (Lake Gusinoye, Bolshebereznikovsky Region). In the middle 1980s rotan became common in flood plain lakes. Density and structure of populations of rotan attain peak values in the middle 1980s up to 100,000 individuals of varied age. In 1990 its numbers declined notably (Vechkanov, 2000).
Moreover, rotan became spread in a number of adjoining Volga regions of Tula, Ryazan, Kaluga, Vladimir, Nizhni Novgorod, Samara and also republics Tatarstan and Mari (Kudersky, 1980; Elovenko, 1981; Zaloznykh, 1982). According to the fisheries statistics catch if this fish in middle Volga in 1988 was 1.6 tons, in 1989 0.9 tons (Kudersky, Shimanovskaya, 1995).
In the basin of the Upper Volga rotan appeared in 1970 and in Yaroslavl Region it began spreading in the 1980s inhabiting in stagnant water bodies and water bodies with weak flow, mostly ponds and sand pits. In 1990 it was recorded in the region of Pleshcheyevo Lake, in Yaroslavl Region (Shlyapkin, Tikhonov, 2001; Kozlov, 1993). Rotan became spread in the national park Zavidovo (Upper Volga basin). It occurs in ponds, former river beds, ditches, overgrown shallow water areas of Shoshinsky reach of Ivan'kovskoje water reservoir (Fertikov, 1998).
White Sea basin
Later it began occurring in regions situated further north.
In the middle 1990s rotan was noted in ponds of Vologda and also in Lake Plestsy in Plesetsky District
of Arkhangelsk Region where it
appeared approximately in 1994-1995. Reported from the Vychegda river system (Boznak, 2003)
(
Northern Dvina drainage area, White Sea, Polar Ocean basin).
Acclimatization of rotan in water bodies of Middle Asia in Lake Baikal basin may be regarded as a transition to new areas situated in the same latitudinal zone as the natural distribution range of the species. Unlike this, introduction of rotan in water bodies of the European part of the former Soviet Union, its shift to the north (approximately by 10 degrees latitude) to the geographic zone, new for the species. Successful naturalization in water bodies of this territory is the evidence of wide ecological plasticity and potential of the species (Kudersky, 1982).
On the basis of genetic research it is assumed (Ilyin, 1987) that rotan was brought only once to the regions of Leningrad and Moscow.
Kozlov (1993) proposed conventional calculations of rate of expansion of rotan distribution range. Under conditions of branched river network rotan needed 25 years to move from Moscow by 300 km and reach Volga (12 km per year). Volga is a powerful current and its population extended its distribution range to Samara, i.e.5 times more rapidly (67 km per year), than before. With this rate of dispersal rotan will appear in Astrakhan by 2010. Single individuals will be found earlier. Approximately the same pattern of dispersal of rotan may be expected in the Don River. In the west dispersal of rotan is restricted because of the absence of connection between the Volga River basin and Zapadnaya Dvina. This does not concern the north-western direction - Baltic basin where owing to the mild climate it will disperse probably at a rate of 10-12 km per year.
< back | up | next >
